The oil spill that reached Brazilian Coast in 2019 was one of the most extensive disasters and its effects on distinct species are still under investigation. This study evaluated the effects of the oil spill on the crab Pachygrapsus transversus in four reef areas in Northeast of Brazil that are also under different levels of chronic anthropogenic impacts. Changes in population aspects were investigated including maturity, sex ratio, and relative growth considering periods before and after the oil spill. An acute decrease in the number of females captured in areas most affected by oil spill was evident and may be associated with the closure of burrows used for protection. Crabs from the most touristic area presented a decrease in the medium size of carapace and maturation compared to crabs from other less visited areas, which highlights the importance of studying the effects of impacts on marine fauna.

In this study, we aimed to identify impacts of plastic ingestion by the ecologically important rocky shore crab Pachygrapsus transversus. We sampled individuals from August 2019 to January 2020 in a reef environment and determined their body condition and diet diversity. In order to test our hypothesis that plastic retention in the foregut is able to decrease the condition factor, we compared it between contaminated and non-contaminated individuals. A correlation test of number of ingested plastic fibres against trophic diversity was made to corroborate the hypothesis that plastic ingestion modifies the feeding patterns. Our results demonstrated that contaminated individuals had lower body condition. Also, we confirmed that debris ingestion can influence feeding patterns. These outcomes were probably linked to starvation and nutrient loss effects. We discussed that this crab is a potential sentinel specie for addressing impacts of solid pollution and a candidate for monitoring plastic contamination in reef environments.

The Columbus crab Planes minutus and Arch-fronted swimming crab Liocarcinus navigator, within their distribution ranges in the Mediterranean, were found rafted on plastic macro-litter floating on the open south Adriatic. While P. minutus was recorded from inanimate flotsam outside of the Mediterranean, L. navigator is herein reported for the first time on floating marine litter. The role of floating litter as habitat or as a dispersal agent for marine invertebrates has received quite attention however, records of decapod crabs drifting on litter has been relatively sparse. Our results suggests that vast quantities of floating debris, comprised primarily of non-biodegradable plastic polymers, probably will augment natural floating substrates in the marine environment, potentially facilitating the spread of invasive species. The dispersion of rafting crabs through floating debris should be investigated given the high potential ecological risk of invasion by exotic species due to the increase in waste production (ecological risk assessment).